Digitally receptive coating method

ABSTRACT

A digitally receptive coating method includes the steps of applying a digitally receptive coating to a first side of a film, metalizing the first side of the film and bonding the metallized first side of the film to a substrate to produce a laminate having a digitally receptive coating.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/761,370, filed on Feb. 7, 2013, which claims thebenefit of U.S. Provisional Application No. 61/595,791, filed Feb. 7,2012, each of which are incorporated by reference herein in theirentireties.

FIELD OF THE INVENTION

The present invention relates generally to a digitally receptive coatingmethod and, more particularly, to a digitally receptive coating methodusing transfer lamination.

BACKGROUND OF THE INVENTION

Currently, a laminate is manufactured using a paper stock that has aclay coating on both the face and the back sides. The clays coatingimparts certain desirable qualities to the paper such as surface gloss,smoothness and reduced ink absorbency. Such double coated papers areutilized in the packaging industry, for postcards, for advertisingmaterials and in magazines.

As is currently known in the art, such a clay-coated laminate may bemade using transfer lamination. Transfer lamination is a process bywhich a layer of material is applied to a substrate. Generally, transferlamination involves bonding a transfer film having a application layer,e.g., a metallized layer, to a paper substrate, stripping the film fromthe substrate leaving the application layer, and then applying a coatingto the layer to facilitate printing. As will be appreciated, thisprocess typically involves multiple, separate steps.

In particular, an untreated film, such as a polyester film, that has amicro-embossable coating that has been micro-embossed and metallized islaminated to the face side of a clay-coated paper substrate using awater-based adhesive. The film layer is then stripped away, leaving themicro-embossable coating and metalizing on the face side surface. Adigitally receptive coating is then applied to the laminated sheet.

A drawback to this method is that when the digitally receptive coatingis applied to the front side of the laminate, the clay coating on theback side can “offset” or transfer to the front side of the laminateduring storage. This is due in part to the paper laminate being wound uptightly in a roll after the digitally receptive coating is applied. Inparticular, as the finished laminate is being wound up into a roll,inter-layer slippage and/or rubbing between the front and back sides ofthe laminate may cause the clay coating on the back of the laminate totransfer to front of the laminate and adhere to the digitally receptivecoating. Moreover, the digitally receptive coating on the front of thelaminate is generally soft and acts like a quasi-adhesive under thetension of being wound in a roll, causing specs of the clay coating topull from the back side of the laminate and stick to the digitallyreceptive coating on the front side. As a result, the digitallyreceptive coating may have specs of clay adhered thereto which canresult in the finished laminate being “milky” or “hazy” in appearance.

In view of the above, it is desirable to produce a laminate wherein claytransfer and marring is minimized. Moreover, a need exists for adigitally receptive coating method which eliminates or reduces claytransfer. As discussed in detail herein, the present invention addressesthese needs.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a digitallyreceptive coating method.

It is another object of the present invention to provide a digitallyreceptive coating method that utilizes transfer lamination.

It is another object of the present invention to provide a digitallyreceptive coating method whereby clay transfer is eliminated or reduced.

It is another object of the present invention to provide a digitallyreceptive coating method whereby a produced laminate may be stored inroll form without substantial clay transfer.

It is another object of the present invention to provide a digitallyreceptive coating method whereby the digitally receptive coating issubstantially smooth as compared to existing methods.

It is another object of the present invention to provide a digitallyreceptive coating method in which a digitally receptive coating isapplied to a transfer film.

These and other objects, features and advantages of the presentinvention will become apparent in light of the detailed description ofthe best mode embodiment thereof, as illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating a prior art method for transferlamination.

FIG. 2 is an illustration of a prior art transfer film construction.

FIG. 3 is an illustration of a prior art laminate construction at apoint prior to removing the transfer film.

FIG. 4 is an illustration of a prior art laminate construction after thefilm has been removed and a digitally receptive coating applied.

FIG. 5 is a flowchart illustrating a digitally receptive coating methodin accordance with an embodiment of the present invention.

FIG. 6 is an illustration of a transfer film construction in accordancewith an embodiment of the present invention.

FIG. 7 is an illustration of a laminate construction in accordance withan embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2 , known processes for producing a clay-coatedlaminate having a digitally receptive coating for digital printinginvolve the following general steps. The first of these steps, labeledwith reference numeral 10, is to coat an untreated polyester film 12with a micro-embossable coating layer 14. The film 12 is then eithermetallized, as shown at step 20, or micro-embossed and then metallized.The step of metallization involves placing the film 12 in a largemetallizer where metals, such as aluminum 16, are vacuum deposited ordeposited by other means known in the art, on the film 12. Theconstruction of the transfer film after metallization is shown in FIG. 2. As shown therein, subsequent to metallization, the transfer filmincludes an untreated polyester film 12, a micro-embossable coatinglayer 14, and a metal layer 16.

Once the film has been metallized, it is bonded to a paperboardsubstrate 18 in a third step, represented by reference numeral 30. Inthis step, a water-based adhesive 22 is applied to the film and the filmis laminated to the face side of a paperboard substrate 18 (having aclay coating on both sides). Alternatively, the adhesive 22 may be asolvent-based adhesive, energy curable adhesive, or other type ofadhesive known in the art, without departing from the broader aspects ofthe present invention.

The construction of the laminate following step 30 is shown in FIG. 3 .As shown therein, the construction includes a paperboard substrate 18with a clay coating on both the face and back sides, a water-basedadhesive layer 22, a metal layer 16, a micro-embossable coating layer 14and the untreated polyester film 12 forming the top layer.

As shown in step 40, the film is then stripped off, leaving the thinmetal layer 16 bonded to the paper substrate 18. At step 50, a digitallyreceptive coating 24 is then applied to the face side of the laminate.This digitally receptive coating allows for digital printing, such astext, designs, pictures or the like, on the laminate. This process isdescribed in further detail in U.S. Patent Application Publication No.2010/0314036, which is hereby incorporated by reference herein in itsentirety.

As shown in FIG. 4 , once the film 12 is stripped off and the digitallyreceptive coating applied, the finished laminate construction includes apaperboard substrate 18 with a clay coating on both the face and backsides, a water-based adhesive layer 22, a metal layer 16, amicro-embossable coating layer 14 and a digitally receptive coating 24on top.

As discussed above, however, this process may be problematic, especiallywhen the laminate is wound into a roll for storage and the like. Inparticular, the digitally receptive coating 24 may be sensitive toexcessive pressure such that when the finished laminate is would uptightly in a roll, the digitally receptive coating 24 may adhereslightly to the clay coated back of the laminate and cause an effectknown as “offsetting,” where part of the clay coating transfers to thedigitally receptive coating 24, causing an unsightly, “hazy” look. Rollsof laminate produced by this method, therefore, must be sheetedimmediately to minimize this effect.

Turning now to FIG. 5 , the inventive digitally receptive coating method100 of the present invention substantially eliminates offsetting,leaving the digitally receptive coating 24 with a smooth and mirror-likefinish. The method 100 includes first coating an untreated polyesterfilm 12 with a digitally receptive coating layer 24. This step isrepresented by reference numeral 110. In the preferred embodiment, thedigital coating 24 is applied at a coat weight of approximately 0.15 to0.40 dry pounds per 3000 square feet. Next, a micro-embossable coatinglayer 14 is applied to the digitally receptive coating 24, as shown atstep 120. In the preferred embodiment, the micro-embossable coatinglayer 14 is applied at a coat weight of 0.7-1.5 dry pounds per 3000square feet, although other coat weights are certainly possible withoutdeparting from the broader aspects of the present invention. The film 12is then either metallized, as shown at step 130, or micro-embossed andthen metallized. In an embodiment, metallization involves depositing athin layer of aluminum on the micro-embossable coating layer 14.

At this point in the process, the transfer film construction includesthe untreated polyester film 12, a digitally receptive coating layer 24,a micro embossable coating layer 14 and a metal layer 16. Importantly,the digitally receptive coating layer is actually applied to thetransfer film 12, not the finished laminate, and is intermediate themetal layer and the film 12. This construction is illustrated in FIG. 6.

Once the film has been metallized, it is bonded to a paperboardsubstrate 18 in a fourth step, represented by reference numeral 140. Inthis step, a water-based adhesive 22 is applied to the transfer film 12and then the film 12 is then laminated to the face side of a paperboardsubstrate 18 (having a clay coating on both sides). Importantly, theresulting laminate remains in this state until it is ready to besheeted, at which time the film 12 is stripped/removed. After laminatingthe transfer film to the paper substrate 18, the laminate, including thefilm 12, can be wound into a roll for storage, as shown at step 150.

As will be readily appreciated, after adhering the transfer film to thepaperboard substrate 18, the laminate construction includes a paperboardsubstrate 18 with a clay coating on both the face and back sides, awater-based adhesive layer 22, a metal layer 16, a micro-embossablecoating layer 14, a digitally receptive coating layer 24 and theuntreated polyester film 12 forming the top layer. This construction isshown in FIG. 7 . Importantly, the untreated polyester film 12 is lefton top of the laminate and serves to protect the digitally receptivecoating 24. In particular, when the finished laminate is would into aroll, the film 12 serves as a buffer between the “soft” and “sticky”digitally receptive coating layer 24 and the clay-coated back side ofthe paperboard 18. In this manner, the film 12 prevents the digitallyreceptive coating 24 from contacting the clay-coated back side of thepaperboard substrate 18 while in roll form.

Moreover, because the digitally receptive coating 24 is applied to thefilm 12 prior to laminating the film to the paperboard 18 (rather thanapplying it to the laminate as a final step), the film may be left onthe laminate, rather than stripped off, until just prior to sheeting. Asnoted above, the laminate may then be wound tightly in a roll and storedwithout the clay transfer issue that has hampered prior methods.

When the finished laminate is sheeted, the film 12 is finally strippedoff. The laminate is then sheeted and stacked. As will be readilyappreciated, the interlay pressure is less in sheeted form than in rollform, so the offsetting or clay transfer is minimized or eliminated.

In addition to eliminating the clay transfer issue, waste associatedwith known processes is reduced. Furthermore, the finished surface ofthe digitally receptive coating 24 is much smoother as compared to thefinished surface of the laminate manufactured utilizing known processes.This is a result the fact that the polyester film 12 to which thedigitally receptive coating 24 is applied during the inventive method100 is much smoother than micro-embossable coating layer 14 to which thedigitally receptive coating 24 has been applied in existing processes.The method of the present invention also is more environmentallyfriendly than existing methods, as once the film 12 is finally stripped,the produced laminate is easier to recycle.

Although this invention has been shown and described with respect to thedetailed embodiments thereof, it will be understood by those of skill inthe art that various changes may be made and equivalents may besubstituted for elements thereof without departing from the scope of theinvention. In addition, modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodimentsdisclosed in the above detailed description, but that the invention willinclude all embodiments falling within the scope of this disclosure.

What is claimed is:
 1. A method of forming a laminate construction,comprising the steps of: applying a print receptive coating to a firstside of a film; applying at least one of a micro-embossable coating anda metallized layer to said print receptive coating; and bonding saidfilm with said at least one of said micro-embossable coating and saidmetallized layer to a substrate to form a laminate construction.
 2. Themethod according to claim 1, further comprising the step of: removingsaid film from said laminate construction to expose said print receptivecoating.
 3. The method according to claim 2, wherein: said step ofremoving said film from said laminate construction is carried oututilizing a transfer lamination stripping process.
 4. The methodaccording to claim 1, wherein: said substrate is a paperboard substratehaving a clay coating on a face side of said paperboard substrate and aback side of said paperboard substrate.
 5. The method according to claim1, further comprising the step of: winding said laminate constructioninto a roll such that said film serves as a buffer between saidsubstrate and said print receptive coating.
 6. The method according toclaim 5, further comprising the steps of: unwinding said roll; removingsaid film from said laminate construction to expose said print receptivecoating; and sheeting said laminate construction.
 7. The methodaccording to claim 1, wherein: said step of applying said printreceptive coating to said first side of said film imparts a smoothnessto said print receptive coating that corresponds to a smoothness of saidfirst side of said film.
 8. The method according to claim 1, wherein:said step of bonding said film with said at least one of saidmicro-embossable coating and said metallized layer to said substrateincludes applying an adhesive to at least one of said substrate and/orsaid at least one of said micro-embossable coating and said metallizedlayer.
 9. The method according to claim 1, wherein: said film is apolyester transfer film.
 10. A digitally receptive coating method,comprising the steps of: applying a digitally receptive coating layer toa first side of a transfer film to impart a smoothness to said digitallyreceptive coating layer that corresponds to a smoothness of said firstside of said transfer film; applying at least one of a micro-embossablecoating layer and a metallized layer to said digitally receptive coatinglayer; bonding said transfer film with said at least one of saidmicro-embossable coating layer and said metallized layer to a substrateto form a laminate construction, and in a manner such that said transferfilm is removable from said laminate construction; and winding saidlaminate construction into a roll such that said transfer film serves asa buffer between said substrate and said digitally receptive coatinglayer.
 11. The digitally receptive coating method according to claim 10,further comprising the steps of: unwinding said laminate constructions;and stripping said transfer film from said laminate construction toexpose said digitally receptive coating layer.
 12. The digitallyreceptive coating method according to claim 10, wherein: said substrateis a paperboard substrate having a clay coating on a face side of saidpaperboard substrate and a back side of said paperboard substrate. 13.The digitally receptive coating method according to claim 12, wherein:said transfer film serves as a buffer between said substrate and saiddigitally receptive coating layer to prevent clay transfer from saidback side of said paperboard substrate onto said digitally receptivecoating layer.
 14. The digitally receptive coating method according toclaim 13, further comprising the steps of: unwinding said roll; removingsaid transfer film from said laminate construction to expose saiddigitally receptive coating layer; and sheeting said laminateconstruction.
 15. The digitally receptive coating method according toclaim 10, wherein: said step of bonding said transfer film with said atleast one of said micro-embossable coating layer and said metallizedlayer to said substrate includes applying an adhesive to at least one ofsaid substrate and/or said at least one of said micro-embossable coatinglayer and said metallized layer.
 16. The digitally receptive coatingmethod according to claim 10, wherein: the transfer film is a polyestertransfer film.
 17. A digitally receptive coating method, comprising thesteps of: applying a digitally receptive coating layer to a first sideof a polyester transfer film to impart a smoothness to said digitallyreceptive coating layer that corresponds to a smoothness of said firstside of said polyester transfer film; applying at least one of amicro-embossable coating layer and a metallized layer to said digitallyreceptive coating layer; applying an adhesive to at least one of apaperboard substrate and/or said at least one of said micro-embossablecoating layer and said metallized layer and bonding, via said adhesive,said polyester transfer film to said substrate to form a laminateconstruction; and stripping said polyester transfer film from saidlaminate construction to expose said digitally receptive coating layerhaving a smooth surface.
 18. The digitally receptive coating methodaccording to claim 17, wherein: said substrate is a paperboard substratehaving a clay coating on a face side of said paperboard substrate and aback side of said paperboard substrate; and wherein said method furtherincludes the step of winding said laminate construction into a roll suchthat said polyester transfer film serves as a buffer between saidpaperboard substrate and said digitally receptive coating layer.